Lithium battery charge profiles

[mahendra]

can you elaborate a bit more boB?

[ClassicCrazy]

From the Classic Manual

AUX 1 - Control Settings (12V @ 200Ma or Dry 1A Contact)
SOC % Low
This mode will set AUX1 to 0.0V according to the LOW % and HIGH % settings. HOLD (LOW) and
DELAY (HIGH) activation TIMES can be set in seconds. SOC %=HIGH=0V SOC %=LOW=12V
SOC % High
This Mode will set AUX1 to +12V according to the LOW % and HIGH % settings. HOLD (LOW) and
DELAY (HIGH) activation TIMES can be set in seconds. SOC %=HIGH=12V SOC %=LOW=0.0V
If the classic is set to do an auto-restart at 23:59 (midnight), the state of the AUX1 will be remembered
so it will return to the last state (+12V or OFF) after it resets and comes alive again.

So you can hook up a relay to AUX 1 to control whatever according to what the SOC is .

[Cniemand]

I'm not sure it is inherently bad that Lithiums are at 100%SOC. Rather I feel it is more of a condition where you are dealing with the sharp jump in voltages due to the steep charge curve on the top and lower ends. Plus, not all cells will be the same capacity regardless of manufacturing dates/batches. Thus you find yourself dealing with over-charging some cells in the hopes of getting the others to 100%SOC.

LFP cells work quite well simply using the ENDAMP function. It brings them to what they consider to be fully charged without getting into dangerous sections of the charge curve.  LFP cells use 0.05C for their ENDAMPS. 100aH = 5a or 180aH = 9a (180*0.05=9)

For FLOAT (With the idea of having a full battery when the sun goes down) you need to use a voltage slightly above their resting voltage. In LFP cells that works out to 3.34v (resting). I chose to use 3.375v as it keeps them full while not being enough to slowly overcharge a cell throughout the day.

Whatever you do, stay away from EQUALIZE. No need to cook your cells.

[Cniemand]

Added: I wouldn't trust the ENDAMP function (at face value) unless you are using a WBjr. The WBjr sees exactly what goes into the bank (Already calculating for background loads) so you get an accurate ENDAMP. Without it, as I had lived for a couple years without one, you have to add a few amps to the ENDAMP number to get a rough estimate. I figure that when everything is idle in the house it still consumes 2-3a, so I setup the ENDAMPS to be 8 rather than 5. Since purchasing the WBjr it is safe to bring it back to 5.

I also like having the WBjr because it allows you to fully use your system as soon as you wake up because you do not need to compensate for heavy background loads (possibly over-charging your LFP pack) as it knows what is going in/out of the bank.

In other words.... ME = Happy camper!

[aussiejohnny]

Hello, sorry to kick this one off again. 
But are there any specific charge profiles to set the classic 200 for a 400ah lifepo4 battery bank?   Has anything changed in the past year in regards to how someone using lifep04 batteries has set their classic?
I nearly have my wiring all done, bar picking up my 16x100ah cells in the city next week (swapping them with 4 x 400ah cells i haven't used yet) and wiring them in. 

Thanks.

[ClassicCrazy]

Hello, sorry to kick this one off again. 
But are there any specific charge profiles to set the classic 200 for a 400ah lifepo4 battery bank?   Has anything changed in the past year in regards to how someone using lifep04 batteries has set their classic?
I nearly have my wiring all done, bar picking up my 16x100ah cells in the city next week (swapping them with 4 x 400ah cells i haven't used yet) and wiring them in. 

Thanks.

Are you planning on using bottom balancing ?
Are you going to have any kind of BMS protection ?
I would make sure you have something independent of the Classic to disconnect if voltage goes too low.

Larry

[aussiejohnny]

Hi Larry. 
No i top balanced my cells. 
Will not be using a BMS. 
Will be getting a control box fitted that automatically deals with lvc and hvc.

System has been running 3 days now, We are completely running off the battery bank.  Very impressed in these lifepo4!  Running my 6kw ac for 3 hours was easy for them.

Still learning the classic 200 though for fine tuning.

Thanks for your reply.

[RossW]

picking up my 16x100ah cells in the city next week

Very impressed in these lifepo4!  Running my 6kw ac for 3 hours was easy for them.

I'm obviously missing something here.
3.2V/cell * 100 AH = 320 watt-hours per cell * 16 = 5,120 watt-hours or 5.12kWh
6kW AC, even without inverter losses or cables (assuming the compressor was running!) would use 100% of your batteries capacity in 51 minutes.

For it to have run for 3 hours and have anything left in the tank, your draw has to have been under 1.7 KW average, and probably closer to 1KW? Guessing it was the fan only for 75% of the time and compressor running only about 15 minutes in the hour??

(Been running my 300AH/48V LFP bank for 3 years and also love it to bits. Will be adding 600AH to it for this winter)

[aussiejohnny]

on the main unit outside it states max draw for cooling is 1590 watts.  so far according to my victron bvm i have seen a max of 900 watts draw.  and since putting the ac in economy mode even less while it cycles.
it's a fujitsu system, cooling has 6kw output with 1.59kw input. 

today it's been running for 2 3/4 hours and my battery is still gaining in charge from the panels.

[offgridQLD]

Most small split systems 2.5kw or so have energy coaficiany of 4 to 6 so you get 400 600% more heating or cooling  power out of them than you feed in to them.

As they get larger 5kw and up his typically drops off to more like 300 400%. Usually just because of scale phisical size of the condensor and evaporator needed to keep the same eficiancy as the smaller units wouldn't be astheticaly acceptable in a demestic setting. As in a 5kw unit isn't double the size of a 2.5kw

Part of the reason why I went for several small units than one big one.

[aussiejohnny]

today was a stinker and i have had the ac on since 10am. my battery has been accepting charge from the solar and gone from 64.4% at 7.30 this morning to 95.6% at 1.02pm. (i think i have the victron bvm set up right, without large load the cell voltages from the cellog8 match well with what soc % the bvm shows.

8 1/4 hours total the split system ran for today. i turned the a/c off where the sun was on a fair angle and i was down to 128 watts input but still had 92.9% charge.

getting about 5-11mv difference between the highest and lowest cell according to the celllog8. i think i have set it up right, still a bit to learn in the fine tuning of the classic 200.

[Solar trucker]

I recently took in a very informative seminar in Arizona regarding the RE-LION Lithium Batteries. Has anyone had any
experience with these?  They boast a full 5 year unconditional replacement warranty.  Also pricing seems to be coming down
to a point that is within reach of the average individual.

I've included a PDF file here for your perusal...

[ClassicCrazy]

I recently took in a very informative seminar in Arizona regarding the RE-LION Lithium Batteries. Has anyone had any
experience with these?  They boast a full 5 year unconditional replacement warranty.  Also pricing seems to be coming down
to a point that is within reach of the average individual.

I've included a PDF file here for your perusal...

Might be okay if they will be around to back up the warranty . But reading their warranty they have a lot of discretion to deny it . The warranty on their website did not say 5 years free replacement.   It looks like they are LiFePo4 which is a good lithium technology and looks like they have some kind of under and over voltage protection built in. Not sure what they have for a BMS to ensure cell balancing or if you have to add that on ?   You can compare to prices with Calb but those you don't have any BMS protections built in but cost less - so you can add that stuff on and compare.  Also you have to take shipping into account .  Look at Calb cells here http://www.electriccarpartscompany.com/

[RossW]

Look at Calb cells here http://www.*********/

Your experience may be different.
My one and only dealing with them left me completely unimpressed with their lack of professionalism, their lies and misrepresentations, and ultimately an "oops" email sent by one of their staff to another that accidently included me.

I'd go so far as to say "dishonest", and I have gone out of my way to find stuff that never touches their grubby paws.

Strong words, but I've got the email trail to back it up.

To bring it back on track... under and over voltage "protection" is a failure device I chose to do without.
My inverter and charge controllers prevent over-voltage, and a backup monitoring-only system would alert me anyway. Under-voltage isn't likely to happen, since my inverter will call for a generator run if SoC gets low, OR voltage gets low, and even if the generator didn't kick in, the inverter low-voltage cutout is above the batteries minimum safe voltage.

I do however monitor individual cell voltages, which I find far more useful anyway.

[aussiejohnny]

i'll be getting a lvc and hvc for my system as a last defence setup.  solar controller is set to max volts so shouldn't overcharge them anyway, but just in case.  the low voltage cut on my inverter is too low, so a lvc will be installed.
my system will be left at stage for long periods of time, so alarms and whistles wont be of use when no one is there to hear them. 
i do not use a bms and will not as i deem it not needed with my system.  i do use a junsi cellog8s for monitoring the cells.

very happy with it all so far anyways. just need to do a little finishing touches, tidy up wires to monitor board etc.